Microelectronics circuits include a variety of different circuit components, and one type of circuit component that is often found in these circuits is a comparator. The comparator is a circuit element with two inputs labeled positive and negative and one output. The output goes either high or low depending upon which input is greater.
As will be appreciated by those skilled in the art, the signals being received by comparators are often noisy. When the input voltage of the received signal is close to the threshold voltage of the comparator, one potential problem is that a small amount of noise can make the voltage at the input rapidly fluctuate to values just above or just below the threshold voltage for the comparator. This can cause output “glitches” that may cause instability in the larger circuit, perhaps a control circuit, for example, that is impacted by the output of the comparator.
Existing solutions outside of the field of memory systems include solutions that employ a Schmidt Trigger. In this regard, one skilled in the art will appreciate that a Schmidt Trigger makes use of feedback, so that the current output state essentially “reinforces” the input value. For instance, if the output state is currently logic “high” (logic ‘1’) there will not be an output transition to logic “low” (logic ‘0’) unless the input voltage drops substantially below a low threshold voltage. Conversely, if the output state is currently logic ‘0’, there will not be an output transition to logic ‘1’ unless the input voltage rises substantially above a high threshold voltage. The difference in the two threshold voltages can be referred to as the hysteresis voltage.
A problem with Schmidt Triggers is that they are not designed to work in memory systems, and therefore the principles of hysteresis have apparently not previously been applied in the context of providing incorrupted strobe signals within a memory system.